WO2023077282A1

WO2023077282A1 - Laser 3d printing method and laser 3d printing device

Info

Publication number: WO2023077282A1
Application number: PCT/CN2021/128269
Authority: WO
Inventors: 刘建业; 牛留辉; 徐卡里; 高文华; 胡高峰
Original assignee: 广东汉邦激光科技有限公司
Priority date: 2021-11-02
Filing date: 2021-11-02
Publication date: 2023-05-11

Abstract

A laser 3D printing method, comprising a printing step: using a printing laser to scan paved powder, such that the powder in the scanned region is fused for formation; an output light spot (10) of the printing laser comprises an inner light spot (11) and an outer light spot (12) surrounding the periphery of the inner light spot, and the energy density of the outer light spot is less than that of the inner light spot. Also disclosed is a laser 3D printing device for implementing the described laser 3D printing method. In the described method and device, residual printing stress can be effectively decreased, the deformation of a printing workpiece is reduced, fine cracks in laser 3D printing are effectively reduced, pores during laser 3D printing are reduced, and printing efficiency is increased.

Description

Laser 3D printing method and laser 3D printing equipment

technical field

This application relates to the field of 3D printing, specifically, to a laser 3D printing method and a laser 3D printing device.

Background technique

Laser 3D printing is a manufacturing technology that uses laser light as an energy source to sequentially heat and fuse the powder laid on each layer to obtain printed parts.

In the laser printing technology known by the applicant, there are relatively serious structural defects inside the obtained printed parts, and complex post-processing techniques are sometimes required to alleviate or eliminate these defects.

Contents of the invention

This application aims to provide a laser 3D printing method to solve the problem of serious structural defects in the internal structure of laser printed printed parts.

The embodiment of the application is realized like this:

An embodiment of the present application provides a laser 3D printing method, which includes:

Printing step: use the printing laser to scan the laid powder, so that the powder in the scanned area is fused and formed; wherein, the output light spot of the printing laser includes an inner light spot and an outer light spot surrounding the outer periphery of the inner light spot, and the energy density of the outer light spot is less than The inner spot.

In this scheme, by using composite output spots with different inner and outer energy densities for printing, the energy of the inner spot is concentrated, which can better melt the powder in the irradiation area to obtain a high-quality and high-density fusion structure, and the outer spot irradiates the powder outside the irradiation area of the inner spot at the same time. Effectively flatten the heat-affected zone, balance the transition between the printing area and the unirradiated powder cold area, and facilitate the smooth powder fusion; moreover, the use of the composite output laser can effectively reduce the printing residual stress and reduce the deformation of the printed workpiece.

In one possible implementation:

The powder is metal powder, the energy density of the outer light spot is 10%-90% of the inner light spot, and the power of the outer light spot is 50-5000W.

In one possible implementation:

The spot diameter of the inner spot is adjustable within the range of 10-300 microns, and the spot diameter of the outer spot is adjustable within the range of 20-1000 microns.

In one possible implementation:

The outer contour radius of the outer light spot is 2-4 times the outer contour radius of the inner light spot.

In one possible implementation:

There are multiple printing laser beams acting on a single layer of powder at the same time, and the multiple printing laser beams are respectively used to print multiple partitions of the printing range of the layer, and the partitions printed by adjacent printing lasers are at the junction coincide.

In one possible implementation:

Multiple powder spreading devices are used to carry out multi-layer powder spreading at the same time, and along the powder spreading direction, the powder spreading device for laying the lower layer of powder is located in front of the powder spreading device for laying the upper layer of powder;

Multi-beam printing lasers are used to scan the simultaneously powdered multi-layer powder, and the scanning position of the printing laser of the lower layer of powder is before the powder layer of the upper layer.

In one possible implementation:

After the printing step, a beam of shaping light is added to scan the surface of the printed part printed and formed by the printing step, so as to improve the surface smoothness.

In one possible implementation:

The inner light spot and the outer light spot are configured to be able to individually control light output;

Among the layers to be printed, some layers are printed in a way that both the inner spot and the outer spot emit light, and some layers are printed in a way that the inner spot does not emit light.

The embodiment of the present application also provides a laser 3D printing method. On the basis of the aforementioned laser 3D printing method, the output light spot includes N circles of light spots arranged sequentially from inside to outside, where N is an integer greater than 2, And the energy density of the Nth circle of light spots from outside to inside is smaller than that of the N-1th circle of light spots.

The embodiment of the present application also provides a laser 3D printing device for implementing the aforementioned laser 3D printing method. The laser 3D printing equipment includes a powder laying device for laying the powder and a laser system for generating the printing laser.

The laser 3D printing device in this embodiment is used to implement the aforementioned laser 3D printing method, which can efficiently print and obtain printed parts with small residual stress.

In one possible implementation:

The laser system includes a laser, an optical system, a vibrating mirror and a focusing lens sequentially connected by an optical path; the laser is used to generate laser light, the optical system is used to collimate and expand the laser beam, and the vibrating mirror is used to control the The scanning position, the focusing lens is used to focus the laser to form the printing laser, and the output light spot is formed at the scanning position.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, so It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

FIG. 1 is a schematic diagram of the output spot of the printing laser in the embodiment of the present application;

Fig. 2 is a schematic diagram of the overlap mode of a plurality of output spots in Fig. 1;

FIG. 3 is a schematic diagram of another output spot of the embodiment of the present application;

Fig. 4 is a schematic diagram of the usage state of the laser 3D printing device according to the embodiment of the present application.

Description of main component symbols:

输出光斑 output spot	1010
内光斑 Inner spot	1111
外光斑 Outer spot	1212

重合区 overlap area	1313
分区 Partition	1414
第一圈光斑The first circle of light spots	10a10a
第二圈光斑 second ring spot	10b10b
第三圈光斑third circle of light	10c10c
3D打印设备 3D printing equipment	5050
铺粉装置 Powder spreading device	5151
激光系统 laser system	5252
激光器 laser	5353
光路系统 Optical system	5454
振镜 Galvanometer	5555
聚焦透镜focusing lens	5656
打印激光 print laser	5757
熔合区域fusion zone	Q1Q1
铺粉方向Spreading direction	Y1Y1

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. The components of the embodiments of the application generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of this application, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" appear " and other indications are based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship that is usually placed when the product of the invention is used. It is only for the convenience of describing the application and simplifying the description, rather than indicating Or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting the application. In addition, if the terms "first", "second" and the like appear in the description of the present application, they are only used to distinguish the description, and should not be understood as indicating or implying relative importance.

In addition, terms such as "horizontal" and "vertical" in the description of the present application do not mean that the components are required to be absolutely horizontal or hang, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", and it does not mean that the structure must be completely horizontal, but can be slightly inclined.

Example

The embodiment of the present application provides a laser 3D printing method, including a printing step: using a printing laser to scan the laid powder, so that the powder in the scanned area is fused and formed; the output spot 10 of the printing laser includes an inner spot 11 and an outer periphery of the inner spot 11 The outer spot 12, the energy density of the outer spot 12 is smaller than the inner spot 11. The shape of the output light spot 10 can be referred to FIG. 1 .

In this embodiment, the composite output spot 10 with different inner and outer energy densities is used for printing, the energy of the inner spot 11 is concentrated, and the powder in the irradiated area can be better melted to obtain a high-quality and high-density fusion structure. The outer spot 12 irradiates the inner spot 11 at the same time. The powder on the periphery of the area can effectively flatten the heat-affected area, making the balance transition between the printing area and the unirradiated powder cold area, which is conducive to the smoothness of powder fusion. Moreover, the use of the composite output laser can effectively reduce the printing residual stress, reduce the deformation of the printed workpiece, effectively reduce the microcracks of laser 3D printing, and reduce the pores of laser 3D printing.

In this embodiment, the outer spot 12 and the inner spot 11 form an output spot 10 that can act synchronously. In the process of moving along the scanning path, the outer spot 12 first passes through a larger range of powder cold area, and the inner spot 11 then passes through a wider range. For a small area that has been affected by the outer spot 12, the synchronous scanning of the inner and outer spots 12 can complete the scanning step of the composite illumination, and the operation efficiency is high; and the irradiation interval of the synchronous scanning of the inner and outer spots 12 is small, avoiding the need In the known technology, the interval time after the previous laser beam irradiation is long and there is heat loss that affects the effect of the first treatment, or it is necessary to use the previous laser beam irradiation with higher energy for the first treatment, which affects the properties of the powder and the scanning fusion forming of the laser.

In some embodiments, after the printing step, a shaping beam is added to scan the surface of the printed part printed and formed by the printing step, so as to improve the surface finish, such as to make the surface finish Ra≤2.0 microns.

In an implementation manner of this embodiment, the powder is metal powder, and correspondingly, the laser 3D printing method is a laser selective melting technology applied to metal. At this time, in this embodiment, the energy density of the outer light spot 12 is set to be 10%-90% of that of the inner light spot 11, and the power of the outer light spot reaches 50-5000W. Tests have found that when the energy density of the outer spot 12 and the energy density of the inner spot 11 are higher than 90%, the irradiated area of the outer spot 12 presents a significant powder melting state, and the outer spot 12 and the powder cold area outside it (referring to the untreated area) There will be a large temperature drop gradient between the powder area receiving laser energy), so that there will be a large internal stress in the formed print; The temperature drop gradient is large, and the powder in the irradiation area of the outer spot 12 is difficult to be effectively treated first, which affects the overall forming quality. When the energy density of the outer spot 12 is set to be 10%-90% of that of the inner spot 11, the residual stress of the printed part meets the requirements of general metal printed parts, and there is no need for complicated post-processing procedures. The specific percentage value can be determined according to factors such as the reflectivity of the printing powder material. For example, for high reflectivity materials, a larger percentage can be used; otherwise, a smaller percentage can be used.

For example, when printing laser high-reflectivity powder materials such as copper alloys, using the internal and external composite printing laser, and setting the energy density of the outer spot 12 to 40%-90% of the inner spot 11, can effectively improve the copper alloy powder. The laser energy absorption rate is beneficial to the printing and forming of copper alloy powder. The applicant found through the analysis that with the printing laser of this nature, the scanning of the outer spot 12 can make the copper alloy powder form a complex micro-nano composite structure, thereby increasing its ability to absorb the laser energy provided by the inner spot 11 . Of course, due to the complex factors affecting the printing process, there may be other factors that increase the absorption capacity.

In this embodiment, optionally, the spot diameter of the inner spot 11 is adjustable in the range of 10-300 microns, and the spot diameter of the outer spot 12 is adjustable in the range of 20-1000 microns, and the adjustment method can be through the existing laser system implementation, and will not be repeated here. Optionally, the outer contour radius of the outer spot 12 is 2-4 times the outer contour radius of the inner spot 11 . In this way, the outer spot 12 can act on the powder within a suitable range around the inner spot 11 in advance to obtain a gentler heat-affected zone.

In a possible implementation, there are multiple printing lasers acting on a single layer of powder at the same time, and the multiple printing lasers are respectively used to print a plurality of subregions 14 of the printing range of the layer, and the subregions printed by adjacent printing lasers 14 partially coincides at the junction. For example, as shown in FIG. 2 (in the figure, the output light spot 10 is used to indicate the position of the printing laser), the single-layer printing range is divided into four partitions 14, and the four partitions 14 are distributed in a matrix. The corresponding printing lasers have four beams, which are used for printing respectively. Each partition 14. Adjacent subregions 14 are partially overlapped at the junctions to form overlapping regions 13 , so that the printed structures of each subregion 14 can be better fused together. In addition to the 2 × 2 division form shown in Figure 2, the division of division 14 can also be 1 × 2, 1 × 3, 2 × 1 or other n × m (n and m are positive integers) matrix distribution division form , and can also adopt circular division or other suitable division forms.

In an optional embodiment, the inner light spot 11 and the outer light spot 12 are configured to be able to individually control the light output; in each printed layer, some layers are printed in a way that both the inner light spot 11 and the outer light spot 12 emit light, and some layers The layer is printed in such a way that the inner spot 11 does not emit light. For example, after every several layers (such as 1 layer, 2 layers, 3 layers or more layers) the inner and outer spots 12 emit light and print at the same time, one or several layers of inner spots 11 are inserted and printed without light. In this embodiment, the outer light spot 12 is used to act on the surface of the formed part at intervals of several layers, so as to achieve heat treatment effects such as structure regulation and surface hardening of the printed part.

Referring to FIG. 3 , on the basis of the aforementioned printing laser with inner and outer two layers of light spots, the output light spot 10 of the printing laser can also be set as N circles of light spots sequentially arranged from inside to outside, N is an integer greater than 2, and from The energy density of the Nth circle of light spots from outside to inside is smaller than that of the N-1th circle of light spots. As shown in Figure 3, N=3, the energy density of the first circle of light spots 10a (the outermost light spot) is 10%-90% of the second circle of light spots 10b (the middle circle of light spots), and the third circle of light spots 10c The energy density (of the innermost light spot) is 10%-90% of that of the second circle of light spots 10b.

Referring to Fig. 4, in this embodiment, optionally, multiple powder spreading devices 51 are used to carry out multi-layer powder spreading at the same time, and in the powder spreading direction Y1, the powder spreading device 51 for laying the lower layer of powder is located at the upper layer The front of the powder spreading device 51 of the powder; the multi-beam printing laser 57 is used to scan the multi-layer powder that is simultaneously powder spreading, and the scanning position of the printing laser 57 of the powder of the lower layer is before the powder spreading device 51 of the upper layer.

Through this setting, multiple layers can be printed at the same time, further improving printing efficiency.

With reference to FIG. 4 , the embodiment of the present application also provides a laser 3D printing device 50 for implementing the aforementioned laser 3D printing method. The laser 3D printing device 50 comprises a powder laying device 51 for laying down the powder and a laser system 52 for generating printing laser light 57 . The laser 3D printing device 50 in this embodiment is used to implement the aforementioned laser 3D printing method, which can efficiently print and obtain printed parts with small residual stress. In some embodiments, the laser system 52 includes a laser 53, an optical system 54, a vibrating mirror 55, and a focusing lens 56 that are sequentially connected by an optical path; the laser 53 is used to generate laser light, and the optical system 54 is used to modify the laser light, collimate and expand the beam etc., the vibrating mirror 55 is used to control the scanning position of the laser, the focusing lens 56 is used to focus the laser to form a printing laser 57 , and form an output light spot 10 at the scanning position. Wherein, the specific structure of the optical path system 54 that can realize processing such as correction, collimation and beam expansion can be set with reference to the schemes recorded in the prior art.

As shown in Figure 4, powder spreader 51 has two groups, is respectively used to spread the powder of upper layer and the powder of lower layer; Lower powder. The irradiation position of the printing laser 57 generated by the laser system 52 located in front of the powder laying direction Y1 is located between the front and rear powder laying devices 51, and irradiates on the lower layer of powder, and forms a scanned and fused fusion in the lower layer on its scanning path. Area Q1: the printing laser 57 generated by the laser system 52 located behind the powder spreading direction Y1 is irradiated behind the powder spreading device 51 at the rear, and irradiates on the upper layer of powder, forming a scanned and fused upper layer on its scanning path The fusion region Q1 of the upper and lower layers is fused and connected between layers, thereby obtaining an integrated structure.

After one multi-layer scan is completed, the scanning position of the printing laser 57 generated by the laser system 52 moves up by one unit (the number of layers in one scan*the thickness of each layer) and continues to scan until the print is completed.

Based on the above description, the laser 3D printing method and the laser 3D printing device 50 of some implementations of the examples of the present application can efficiently print printed parts with small residual stress and small deformation of the workpiece, and some of the implementations are additionally suitable for high reflectivity. Printing of materials.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims

A laser 3D printing method, characterized in that, comprising:

Printing step: use the printing laser to scan the laid powder, so that the powder in the scanned area is fused and formed; wherein, the output light spot of the printing laser includes an inner light spot and an outer light spot surrounding the outer periphery of the inner light spot, and the energy density of the outer light spot is less than The inner spot.
The laser 3D printing method according to claim 1, characterized in that:

The powder is metal powder, the energy density of the outer light spot is 10%-90% of the inner light spot, and the power of the outer light spot is 50-5000W.
The laser 3D printing method according to claim 2, characterized in that:

The spot diameter of the inner spot is adjustable within the range of 10-300 microns, and the spot diameter of the outer spot is adjustable within the range of 20-1000 microns.
The laser 3D printing method according to any one of claims 1-3, characterized in that:

There are multiple printing laser beams acting on a single layer of powder at the same time, and the multiple printing laser beams are respectively used to print multiple partitions of the printing range of the layer, and the partitions printed by adjacent printing lasers are at the junction coincide.
The laser 3D printing method according to any one of claims 1-3, characterized in that:

Multiple powder spreading devices are used to carry out multi-layer powder spreading at the same time, and along the powder spreading direction, the powder spreading device for laying the lower layer of powder is located in front of the powder spreading device for laying the upper layer of powder;

Multi-beam printing lasers are used to scan the simultaneously powdered multi-layer powder, and the scanning position of the printing laser of the lower layer of powder is before the powder layer of the upper layer.
The laser 3D printing method according to claim 1, characterized in that:

After the printing step, a beam of shaping light is added to scan the surface of the printed part printed and formed by the printing step, so as to improve the surface smoothness.
The laser 3D printing method according to claim 1, characterized in that:

The inner light spot and the outer light spot are configured to be able to individually control light output;

Among the layers to be printed, some layers are printed in a way that both the inner spot and the outer spot emit light, and some layers are printed in a way that the inner spot does not emit light.
A laser 3D printing method, characterized in that:

On the basis of the laser 3D printing method described in any one of claims 1-7, the output light spots include N circles of light spots sequentially surrounded from inside to outside, N is an integer greater than 2, and from outside to inside The energy density of the Nth spot is smaller than that of the N-1 spot.
A laser 3D printing device, characterized in that it is used to implement the laser 3D printing method described in any one of claims 1-8;

The laser 3D printing equipment includes a powder laying device for laying the powder and a laser system for generating the printing laser.
The laser 3D printing device according to claim 9, characterized in that:

The laser system includes a laser, an optical system, a vibrating mirror and a focusing lens sequentially connected by an optical path; the laser is used to generate laser light, the optical system is used to collimate and expand the laser beam, and the vibrating mirror is used to control the The scanning position, the focusing lens is used to focus the laser to form the printing laser, and the output light spot is formed at the scanning position.